Switch structure



sept 30, 1958 A. E. GERTH ET AL 2,854,550

SWITCH STRUCTURE Filed Sept. 15, 1956 ATTQRNEYS,

United States Patent O SWITCH STRUCTURE Albert E. Gerth and George F.Embshotl, Cincinnati, Ohio, assignors to lnstitutum Divi ThomaeFoundation, Cincinnati, hio, a corporation of Ohio Application September13, 1956, Serial No. 609,627

12 Claims. (Cl. 200-144) The invention has to do with switch structuresparticularly designed for the handling of heavy amperages at highfrequencies, as in the switching of radio frequency currents. Asignificant though non-limiting application for the invention lifes inthe field of vacuum switches, which term as herein used means switchesthe operating elements of which are enclosed in an evacuated orfluidlled envelope, usually of glass. The invention will be described inan exemplary embodiment having to do with such switches.

It is a primary object of the invention to provide improvements inswitches designed to handle high amperages at high frequencies whichimprovements greatly increase the capacity of the switches to handlesuch currents without increasing the size of the switch assembly.

Since the operating elements of such switches (hereinafter forconvenience termed electrodes) tend to reach relatively hightemperatures in operation both because of the high amperages involvedand because of the skin effects of high frequencies if the switches areheavily loaded, it is an object of the invention to provide structuresin'. which the currents are carried more efficiently, and in which theeffects of high temperatures are minimized.

These and other objects of the invention which will be clear to theskilled worker in the art upon reading these specifications or will bepointed out hereinafter are accomplished by that structure andarrangement of parts of which the aforesaid embodiment will now bedescribed. Reference is made to the accompanying drawings wherein:

Figure 1 is a longitudinal vertical section of a vacuum switch embodyingthe invention.

Figure 2 is an end elevation thereof.

Figure 3 is a partial sectional view showing the mode of operation ofthe movable electrode.

Figure 4 is an enlarged partial section taken along the line 4 4 ofFigure 1.

Figure 5 is an enlarged partial section taken along the line 5-5 ofFigure 3.

Figure 6 is a partial perspective of the contact end portion of themovable electrode las such.

Figure i7 is a partial perspective of the contact end of the movableelectrode with the strip elements in place.

Figure 8 is a partial perspective of the contact end of one of thestrips in the exemplary embodiment.

Figure 9 is a partial perspective view of the same end of the other ofthe strips.

In the figures, 1 designates the glass envelope of a vacuum switchdevice having opposed openings 2 and 3 and a transverse opening 6.Stationary electrodes 7 and 8 are sealed in the opposed openings 2 and3. The inner ends of these electrodes approach each other axially andbear contact members such as molybdenum contacts 9 and 10. Between theopposed ends of the stationary electrodes is located the contact end ofa movable electrode 11 bearing a contact element 12 of suitable metaland operating in such fashion that the contact 12 may be broughtselectively into contact with either of the contact elements 9 or 10.

The manner in which the stationary electrodes 7 and 8 are mounted withrespect to the glass envelope is not a limitation on the broader aspectsof this invention. The stationary electrodes, being normally made ofsome metallic substance such as Kovar suitable for sealing to glass, maybe mounted directly in the openings 2 and 3 in the envelope with theglass fused about them, as has hitherto been usual in this art. Forheavy duty switches, however, it is preferred to mount the electrodes 7and 8 at the center portions of relatively thin flange-like elements orflares 13 and 14 to which the electrodes are joined in a gas-tightfashion as by hydrogen-brazing. The are elements have rims 13a and 14a,and, being made of a metallic material suitable for sealing to glass,are mounted in the envelope 1 in such a way that the glass at theopenings 2 and 3 is sealed directly to the rims of the are elements.Such a structure and the method of making it are described in detail inthe copending application of Albert E. Gerth entitled Mounting forElectrodes in Glass' Vessels, Serial No. 605,121 filed August 20, 1956.The mounting of the electrodes in the glass envelope by means of theaforesaid Hare elements is useful in permitting the electrodes to reachhigher operating temperatures without adversely affecting the seals tothe glass envelope.

The transverse electrode 11 may be mounted, as such, in the usua'lfashion. As illustrated in the drawings there is a metallic thimble 15,one end of which is closed by a metallic diaphragm member 16. Thediaphragmmember has a rim 16a engaging an end of the thimble andhydrogen-brazed or otherwise joined thereto in a gas-tight fashion. Theelectrode 11 passes through the center of the diaphragm member and isjoined thereto in a gas-tight fashion as by brazing. The diaphragm,being flexible, permits a limited movement of the electrode 11 as alever, furnishing a fulcrum for such movement. The opposite end of thethimble 15 is joined to the neck of the glass envelope at the transverseopening 6, the glass being sealed to the metal of the thimble asindicated at 17 in Figures 4 and 5.

It is conventional, moreover, in switches of this type to form themovable electrode of suitable metallic tubing, and to exhaust the vesselof envelope through the electrode 11 by connecting it with a suitablevacuum pump. When the desired vacuum has been attained in the vessel,the electrode 11 is pinched as at 11a and welded or otherwise sealed toprevent re-entry of gas. Normally a getter substance is applied to asupport 18 within the envelope and is fired by the application ofinductive heating through the envelope, in order to clean up the lasttraces of the atmosphere therein.

, The manner in which the switch may be operated is by movement of themovabley electrode 11. It will be seen that the structure is' in effecta single pole, double lthrow switch.

The electrode 12, usually though not necessarily in the shape of arectangular piece of. suitable metal, such as molybdenum, is affixed tothe end of. the movable electrode 11 inside the envelope. There arevarious ways in which this may be done. One way is illustrated in Figure6. The end of the tube is' slotted, the contact member 12 is thrustWithin the slot, and the walls of the tube are welded to both sides ofthe contact member as at 19 `and 20. in order to exhaust the vesselthrough the electrode 11 the slot is left open at the bottom, or alateral opening 21 is provided therethrough if the inner end of theelectrode is closed by the attachment of the contact member.

In the practice of the invention use is made of a pair of strips joinedwith the movable electrode. These strips have their upper end portionsformed or stamped as at 22 and 23 to surround the electrode 11.Excepting at the top, their lateral edge portions may be ared as at 24and 25 so as to yform 1in-like structures. The upper portions of thestrips may thus be placed around the movable electrode and fastenedtogether by spot welding or otherwise as indicated at 26 and 27 inFigure 7.

The strips, juxtaposed as indicated, substantially surround the wholelength of the movable electrode within the envelope and the thimble.

The lower end portions of the strips (in hat condition) are reverselybent upwardly as at 28 and 29 in Figure 5 and then again reverselydownwardly as at 30 and 31 so that their ends lie along inner surfacesof the thimble 15, to which they may be caused to conform, and to whichthey may be joined as by spot welding, brazing or in. other ways. Thereversely bent portions of the strips provide by flexing for movement ofthe movable electrode in the operation of the switch.

The upper end of one at least of the strips is carried upwardly beyondthe end of the contact element 12 and is provided with a cut-out 32disclosing the central portion of the contact element. The outer endportion of the contact element is fastened to the projecting portion ofthe strip as by spot welding at 33. Instead of making the extendingportion a part of one of the strips, it could be made separately andfastened by welding between the ends of the strips 22 and 23.

The strip structure described has several functions. It assists in thecarrying of the current applied to the movable electrode 11. It providesadditional current carrying paths between the movable electrode and thethimble 15, to which contact may be made, thus relieving the diaphragmmember of some current carrying duty. Because of the greatly enlargedsurfaces of the strip structure the carrying of high frequency currentsis made more efficient. Moreover the strips act to some extent asradiators and conductors of heat, permitting the electrode to Operatemore effectively. The iin-like conformation above described assists inthis. The current is transferred in part to the contact element 12through its lower end by the movable electrode 11; but current alsoflows through the extending end portion of the longer strip about theopening 32 and is transferred to the upper end of the contact 12 at theconnection 33. This increases the efficiency of electrical transfer tothe contact member, and minimizes heating effects.

Modications may be made in the structure described as exemplary withoutdeparting from the spirit of the invention. The use of the invention isnot confined to the movable electrode in a structure of the classdescribed but may be applied instead or in addition to other electrodes.The strip structure may, if desired, be brazed or welded to theelectrode with which it is associated, but this is not normallynecessary.

Having described the invention in an exemplary embodiment, what isclaimed as new and is desired to be secured by Letters Patent is:

1. In electrical apparatus of the class described, a metallic,current-carrying electrode of elongated form, a metallic mounting meanstherefor to which a portion of said electrode is attached, and fromwhich said elec* trode extends in one direction, and at least onecurrent carrying strip element lying along the said extent of saidelectrode and aiiixed to said electrode, said strip element having afree end attached to said mounting means.

2. The structure claimed in claim 1 wherein said electrode carries atone end a contact element aixed thereto and projecting therefrom, and inwhich a member united with the said strip element extends beyond and iselec- 4 trically joined with the projecting portion of said contactelement.

3. The structure claimed in claim l including two opposed strip elementsone on either side of said electrode and shaped to embrace saidelectrode.

4. The structure claimed in claim 1 including two opposed strip elementsone on either side of said electrode and shaped to embrace saidelectrode, an electrical contact member attached to the end of saidelectrode, and one at least of said strips having a portion inelectrical union therewith extending beyond said contact member andelectrically joined to the projecting end thereof.

5. The structure claimed in claim 4 wherein the said extending portionis provided with an orifice to disclose said contact member.

6. in a structure of the class described, a vitreous envelope, anelectrode having an end projecting into said envelope and sealed to saidenvelope through the intermediary of a metallic mounting means, and atleast one conductive metallic strip having a portion lying along andaffixed to the electrode within said envelope and another, reverselybent portion attached to said mounting means.

7. The structure claimed in claim 6 wherein a Contact member is attachedto the end of said electrode within said envelope so as to project fromsaid electrode, and in which said strip is electrically joined to theprojecting end of said contact member.

8. In a structure of the class described, an elongated movableelectrode, a metallic thimble, a flexible metallic diaphragm across anend of said thimble, said electrode passing axially through saiddiaphragm, said diaphragm being flexible whereby said electrode iscapable of rocking movement with respect to said thimble, and at leastone metallic strip having a portion lying along said electrode andanother reversely bent portion having an end attached to said thimble.

9. The structure claimed in'claim 8 including a pair of strips widerthan said electrode, one on each side of said electrode, each said striphaving a reversely bent portion with an end attached to said thimble,side portions of said strips extending laterally beyond said electrodebeing separated 'to form fins.

10. The structure claimed in claim 9 wherein a Contact member isattached to the end of said electrode and wherein a portion inelectrical union with one of said strips extends to the projecting endof said contact member and is electrically joined thereto.

l1. The structure claimed in claim 9 wherein a contact member isattached to the end of said electrode and wherein one of said stripsextends to the projecting end of said contact member and is attachedthereto, the projecting end of said strip being provided with an orificeto disclose said contact member.

12. The structure claimed in claim 9 wherein a contact member isattached to the end of said electrode and wherein one of said stripsextends to the projecting end of said contact member and is attachedthereto, the projecting end of said strip being provided with an oriceto disclose said contact member, in combination with at least one otherelectrode entering and sealed to said envelope through aheat-dissipating, thin-walled metallic mounting means, said lastmentioned electrode having a contact element coacting with the rstmentioned contact element.

Crum Oct. 7, 1941 Burton Oct. 4, 1949

